NAME

probe - determine if a non-self-identifying device is present

SYNOPSIS

#include <sys/conf.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
static int prefixprobe(dev_info_t *dip);

INTERFACE LEVEL

illumos DDI specific (illumos DDI). This entry point is required for non-self-identifying devices. You must write it for such devices. For self-identifying devices, nulldev(9F) should be specified in the dev_ops(9S) structure if a probe routine is not necessary.

ARGUMENTS

dip

Pointer to the device's dev_info structure.

DESCRIPTION

probe() determines whether the device corresponding to dip actually exists and is a valid device for this driver. probe() is called after identify(9E) and before attach(9E) for a given dip. For example, the probe() routine can map the device registers using ddi_map_regs(9F) then attempt to access the hardware using ddi_peek(9F) or ddi_poke(9F) and determine if the device exists. Then the device registers should be unmapped using ddi_unmap_regs(9F).

To probe a device that was left powered off after the last detach(), it might be necessary to power it up. If so, the driver must power up the device by accessing device registers directly. pm_raise_power(9F) will be not be available until attach(9E). The framework ensures that the ancestors of the node being probed and all relevant platform-specific power management hardware is at full power at the time that probe() is called.

probe() should only probe the device. It should not change any software state and should not create any software state. Device initialization should be done in attach(9E).

For a self-identifying device, this entry point is not necessary. However, if a device exists in both self-identifying and non-self-identifying forms, a probe() routine can be provided to simplify the driver. ddi_dev_is_sid(9F) can then be used to determine whether probe() needs to do any work. See ddi_dev_is_sid(9F) for an example.

RETURN VALUES

DDI_PROBE_SUCCESS

If the probe was successful.

DDI_PROBE_FAILURE

If the probe failed.

DDI_PROBE_DONTCARE

If the probe was unsuccessful, yet attach(9E) should still be called.

DDI_PROBE_PARTIAL

If the instance is not present now, but may be present in the future.